1. Field of the Invention
This invention relates to the processing of poultry. Specifically, it relates to a method of preparing poultry exhibiting excellent tenderness characteristics wherein the conventional step of extended, low temperature aging of the defeathered and eviscerated poultry carcasses can be eliminated. More specifically, the invention relates to a method of processing poultry wherein the carcasses are maintained at substantially normal body temperature throughout the process and in which the carcasses, prior to defeathering and eviscerating, are subjected to a relatively short, high temperature conditioning step in a warm humid atmosphere, during which intermittent electrical stimulation is applied to the birds. In this process the subsequently eviscerated carcasses or cut-up parts are injected with a phosphate- and salt-containing solution to further improve tenderness.
2. Description of the Prior Art
Traditional methods of processing poultry typically begin by killing the poultry and bleeding it, usually by cutting the bird's jugular vein. Either before or during the killing, the bird is subjected to an electrical shock. The purpose of this shock is to stun (render semi-conscious) the poultry so that it does not struggle and jump about during the processing steps before rigor mortis sets in, thereby facilitating continuous automatic processing (e.g. on a shackle line). This struggling can cause broken wings and other bruises to the poultry, thereby reducing the value of poultry. The stunning can also make the removal of feathers easier.
After killing and bleeding, the carcass is usually scalded to make the removal of feathers easier. Next, the carcass is defeathered, and then eviscerated. Deterioration of the eviscerated carcass during the extended traditional processing scheme must be avoided, so its temperature at this point is reduced to about 40.degree. F., typically by chilling the carcass in an ice or cold water bath. The chilled carcass is then aged at this low temperature for an extended period of time (e.g. on the order of about 4 to 12 hours) to provide the required degree of tenderness.
After low temperature aging, the carcasses are drained and can be prepared for distribution either raw or cooked, deboned or on the bone. Further, the carcass can also be cut into pieces before distribution or cooking. If the poultry is cooked, cooking time is extended by the time necessary to raise the temperature of the meat from about 40.degree. F. to the cooking temperature. Finally, the parts or carcasses are packaged for distribution.
In an alternative processing scheme, the poultry is shocked after it is "stuck", i.e., after the jugular vein is cut. The purpose of the shock is to numb the bird so that it is not damaged by struggling. Such a scheme is described in U.S. Pat. No. 3,474,490. Stunning after slaughter also results in increased bleeding.
Both of the described processing schemes have proven to be unsatisfactory because of the long time between slaughter and shipment and the high energy consumption and capital costs associated with the process. The time required to obtain deboned raw flesh is typically up to 51/2 hours. An additional up to 31/2 hours is required for cooking and subsequent processing, including the time required to heat the poultry from the chilling temperature (approximately 40.degree. F.). The capital costs for these systems can be substantial when commercial quantities of poultry are to be processed. The cost of aging facilities, chill tanks, ancillary equipment, and consumables such as ice, refrigeration, and the energy used to cool, reheat, and cook, must be considered. Even the methods of including agents intended to improve the organoleptic quality by tenderizing the meat and reducing weight loss due to moisture evaporation, as described in U.S. Pat. No. 3,104,170, have proven to be unsatisfactory in some respects.
The goal of shortening poultry processing time while producing an organoleptically pleasing product have been illusive. The method taught in U.S. Pat. No. 2,129,968 attempted to shorten processing time by simultaneously slitting the throat of the bird while shocking it through the knife. The shock is said to cause convulsive muscle contraction, thereby expelling the blood from the body instantly. This contraction is also said to empty the bird's stomach and crop. During both slaughtering periods when the birds are conveyed to the knife and from the knife to the defeathering operation, the poultry is conditioned in warm, approximately 120.degree. F., high humidity air, in preparation for feather removal. This treatment is utilized in place of the traditional scalding step prior to the defeathering. However, a reasonable estimate of the amount of time saved by this process step is less than about 20 minutes. This saving is relatively insignificant, however, because the remainder of the traditional process, including chilling and lengthy aging, must be faithfully practiced.
It is an object of this invention to provide a method of poultry processing which greatly reduces the energy consumption and time required as compared to the conventional processes.
It is another object of this invention to provide a method of producing organoleptically superior poultry while eliminating the aging period.
It is a further object of this invention to provide a method for poultry processing which, by substantially shortening the time required for processing, obviates the need for refrigeration until after the poultry is cooked or is ready to be packaged for sale.